Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/02—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
  • B05D3/0209—Multistage baking
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
  • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
  • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
  • C08G73/1067—Wholly aromatic polyimides, i.e. having both tetracarboxylic and diamino moieties aromatically bound
  • C08G73/1071—Wholly aromatic polyimides containing oxygen in the form of ether bonds in the main chain
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31721—Of polyimide

Definitions

• the present invention is concerned with a process for coating a substrate with a polyimide.
• the process is easily carried out to yield a coating simultaneously having good planarization and good mechanical and thermal stability.
• U.S. Pat. No. 3,565,549 is concerned with reinforced laminates, and discloses the preparation of polyimide prepolymer and its subsequent curing.
• the patent also summarizes much of the prior art. None in the patent, however, suggests the esters of the present invention. The same is true about U.S. Pat. No. 3,745,149, which also shows curing of a prepolymer.
• a substrate is coated by applying thereto an oligomer and an ester.
• the oligomer is an amino-terminated one, formed from an aromatic diamine and from an aromatic dianhydride.
• the ester is formed from an aromatic tetracarboxylic acid, and from certain alcohols.
• the novel feature of the present invention lies in the particular type of alcohol which is used and in the processing conditions. To obtain the desired results of ease of handling, good planarization and good thermal and mechanical stability, the ester must be one which reacts with an amine group of the amino terminated oligomer to form a high molecular weight polyamide at a temperature between 40° C. and 140° C., and which continues to react to form a cyclic imide.
• esters which meet these requirements are those from alcohols which are activated by being substituted with an electron withdrawing group.
• the most preferred alcohols are CF 3 --CH 2 --OH and ##STR1##
• Other useful alcohols include, for example, hydroxyacetone, trichloroethanol, 1,3-difluoro-2-propanol, ethyl-2-hydroxyiso butyrate and diethyl tartronate, or in fact any alcohol which yields an ester which will react to form a polyamide within the range of 40°-140° C.
• the aromatic tetracarboxylic acid portion of the ester may be from any of such acids known in the art, and shown, for example, in the patents referred to above.
• Preferred acids include pyromellitic acid and benzophenone tetracarboxylic acid.
• the aromatic diamine portion of the original reactants may be any of the aromatic diamine known to the art and referred to in the above patents.
• the most preferred material is oxydianiline.
• the prepolymer is preferably applied to the substrate in the form of a solution in a solvent.
• solvents include, for example, polar organic solvents such as N-methyl pyrolidone, DMSO (Dimethylsulfoxide), Dimethyl acetamide, Dimethyl formamide and mixtures with other solvents.
• an oligomer of the proper type When an oligomer of the proper type is used in the present invention at a temperature of from 40° C. to 140° C., there occurs a reaction between the ester and the amine group to form a high molecular weight polyamide, and reaction continues to form a cyclic imide. It is preferred that the oligomer have an initial molecular weight between 500 and 10,000, and most preferably between 1,000 and 5,000.
• the dichloromethane was removed by means of a rotary evaporator yielding the triethylammonium salt of the desired diester as a viscous, amorphous mass.
• This material was now dissolved in approximately 750 ml of distilled water and the solution gradually added to cold, dilute aqueous HCl causing the desired product to precipitate as a white, flocculant mass. This was immediately filtered and thoroughly washed with distilled water. Drying of the product in vacuo at 60 degrees C. for 24 hours gave the pyromellitic acid ethylglycolate diester in quantitative yield.
• NMR characterization of the product in a mixture of deuterated chloroform and dimethylsulfoxide exhibited a multiplet at 8.2 ppm, a singlet at 4.8 ppm, a quartet at 4.2 ppm and a triplet at 1.2 ppm in the ratio of 1:2:2:3 in accordance with the projected spectrum of the desired product.
• the amorphous residue was dissolved in 250 ml of distilled water and added to a cold, dilute aqueous HCl solution causing the precipitation of a non-crystalline material.
• the supernatant was decanted and thoroughly extracted with diethyl ether and the remaining amorphous precipitate also dissolved in diethyl ether.
• the ether fractions were combined and dried over calcium chloride. Filtration and evaporation of the diethyl ether gave an off-white crystalline material in approximately 60% yield.
• NMR characterization of the product in deuterated acetone exhibited a multiplet at 8.1 ppm, a multiplet at 4.3 ppm, and a multiplet of peaks at 1.7 and 1.0 ppm in the ration of 1:2:3:6 in accordance with the desired structure.
• DP refers to the degree of polymerization and is the number of amide bonds per oligomer unit.
• the resulting viscous solution was next aged for 2 weeks at ambient temperature, sealed in sample bottles and stored in the refrigerator. All operations were performed under the exclusion of moisture and oxygen in an environmental chamber, yielding the oligomer solution ready for further formulation with the diester at a total solids content of approximately 25 wt %.
• the above illustrated formulations were spun-cast onto glass slides and cured to elevated temperatures (300 degrees C.) under a nitrogen atmosphere.
• the curing temperature profile started at 50° C. and proceeded at 5°/min to 100° C. where the temperature was held for one hour.
• the specimen was heated to 135° C. at 5°/min and held at this temperature for two hours.
• the temperature was slowly raised at 0.5°/min to a final temperature of 400° C.
• Removal of the cured films from the glass substrate and examination of the films by IR spectroscopy revealed spectra identical to the polyimide obtained from thermally curing high molecular weight polyamic-acid based on the same monomers (pyromellitic dianhydride and oxydianiline).
• Sample No. 1 is a commercially available high molecular weight polyamic acid based on PMDA-ODA pyromellitic dianhydride and oxydianiline, included for purposes of comparison.
• Sample No. 2 is the formulation based on ethyl glycolate, as prepared above.
• Sample No. 3 is the formulation based on trifluroethanol, as prepared above.
• Sample No. 4 is the formulation based on iso-amyl alcohol, and is included for purposes of comparison.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Macromolecular Compounds Obtained By Forming Nitrogen-Containing Linkages In General (AREA)
• Paints Or Removers (AREA)

Priority Applications (4)

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Publications (1)

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Cited By (12)

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Citations (5)

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• 1983
  • 1983-03-29 US US06/480,164 patent/US4467000A/en not_active Expired - Lifetime
  • 1983-11-30 JP JP58224564A patent/JPS59179667A/ja active Granted
• 1984
  • 1984-02-08 EP EP84101277A patent/EP0120242B1/fr not_active Expired
  • 1984-02-08 DE DE8484101277T patent/DE3461935D1/de not_active Expired

Patent Citations (5)

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